The present invention relates to an electro-mechanic calendar timepiece.
In the electro-mechanic timepieces, the gearing of the movement can float or drift, that has for consequence, especially, that the seconds hand is floating too, due to the fact that this gearing is not submitted to the action of an antagonist torque applied to one of its end, as it is the case of the gearings of the mechanic watches ending by an escapement device.
In the calendar electro-mechanic watches, the driving mechanism of the calendar, when it is not at rest, produces on the gearing an antagonist torque which prevents this undesired floating. Now, in such watches, and even in the case where the calendar indicator, for instance the date indicator, goes step by step instantaneously, that necessitates that the winding of a driving spring be effected during a period of time extending on several hours, there is always a period of some hours during which the driving mechanism of the calendar indicator is at rest and does not apply, consequently, any antagonist torque on the gearing of the movement. The floating of this gearing and, consequently, the corresponding floating of the seconds hand, which is the only one practically visible, is produced during this period.
The object of the present invention is to prevent this drawback.
The invention is applied to a calendar timepiece in which the driving mechanism of at least one indicating member of the calendar, by the motor of the timepiece, is generator of an antagonist torque preventing the floating of the gearing of the movement, this timepiece being characterized by the fact that it comprises a braking device acting on the gearing when the driving mechanism of the indicating member is at rest, so as to produce then an antagonist torque which is substituted to the antagonist torque due to the said mechanism, this braking device being controlled by the even mechanism driving mechanism of the calendar indicating member, so that its action be exactly synchronised with this latter.